1. Field of the Invention
The present invention relates to a compressor, particularly to one that is operated by a brushless DC motor, abreast of a compression device, achieving a brushless DC compressor in micro-miniature form with stronger torque and greater efficiency in compression with the speed-change function of a driving mechanism.
2. Description of the Related Art
Conventional air-conditioners usually have a reciprocating compressor or one with rolling piston to operate with refrigerant. Such compressors have large volume and would distribute heat; therefore they are more suitable to be installed outdoors instead of indoors or in small space.
The air-conditioning compressors used in cars are mostly driven by the engines, but when the engines are turned off, the air-conditioning compressors would not be able to operate, causing the temperature in the cars rising and the people sitting in would not be able to stand the hot. On the other hand, if the engine is kept running to operate the air-conditioning compressors for the people in the car when the car is parked, it would be a waste of energy and the carbon dioxide emission would cause environmental pollution as well. Also, idling for over certain period would break the law.
There are some other air-conditioning compressors have a DC motor to drive the motor to operate the compression and recycling of the refrigerant to cool down the air in the cars. However, such structure has a design of eccentric shaft in the DC motors which would cause the unbalanced driving force of the motors, producing more shakings and louder noises during the operation. Also, there are problems of the sparks due to the operation of the brushes and the electromagnetic interference when the DC motors with brushes are operating. Besides, most DC compressors have the axis of the motor sharing the same axis with the operation axis of the compressor. Since the compressor and the motor both have high rotation speed, the torque would be too weak and the machine would not be able to change the speed, resulting in poor compression efficiency.
With the problems disclosed above, there is still room for improvements.